High frequency quadrature signal generator

[kent]

Hi All

I would like to build a synchronous detection circuit for detecting the real and imaginary part of the signal (I and Q value), the operating frequency for the system is 20 MHz...I would like to know is there any existing chip that can generate the quadrature signal for me (cos wave and sine wave)? And I have never used a crystal as a signal source before...and anyone please give me some application tips about using crystal...Thanks

Kent

 

[berkeman]

To generate a quadrature signal, you can use a phase-locked loop (PLL):

http://en.wikipedia.org/wiki/Phase_locked_loop

And you would probably use Gilbert cell multipliers to do the detection, I would think:

http://www.odyseus.nildram.co.uk/RFIC_Circuits_Files/MOS_Gilbert_Cell_Mixer.pdf

 

[ravenprp]

Hi Kent, thank you for reaching out and sharing your project idea with us. A high frequency quadrature signal generator is a useful tool for many applications, so it's great that you are looking to build one.

To answer your question, there are indeed existing chips that can generate quadrature signals for you. One example is the ADL5380 from Analog Devices, which is a high frequency quadrature demodulator and modulator. It operates at up to 6 GHz and has an integrated LO buffer, making it ideal for your 20 MHz operating frequency. Other options include the MAX2022 from Maxim Integrated and the HMC313 from Hittite Microwave.

As for using a crystal as a signal source, it is a common and reliable method for generating accurate and stable frequencies. The key is to choose the right crystal for your desired frequency and application. You will also need to design a proper oscillator circuit around the crystal to ensure a clean and stable output signal. There are many online resources and tutorials available that can guide you through this process.

Overall, my tips for using a crystal as a signal source would be to carefully select the crystal, design a proper oscillator circuit, and pay attention to factors such as temperature and voltage that can affect the crystal's performance. I hope this helps and best of luck with your project!